1709. Influenza Surveillance in the U.S. Department of Veterans Affairs (VA): 2019-2020 Season

Abstract

Background: VA conducts annual surveillance for seasonal influenza. VA's large elderly population is at higher risk for influenza complications, including hospitaliza-tion and death. Herein we summarize VA's 2019-20 national surveillance data for influ-enza activity and vaccinations.Methods. Influenza telephone triage, influenza-like-illness (ILI) encounters and antiviral prescriptions plus outpatient visits, laboratory testing (antibody tests excluded), hospitalizations and deaths for influenza were obtained from VA data sources (9/29/19-5/16/20) and compared to prior seasons and national CDC FluView data. Influenza vaccinations were captured starting 8/1/2019. Vaccination rates were calculated based on VA users during the fiscal year.Surveillance metrics are presented (Table). ILI visits ranged from 0.9%-3.1% during the season. Influenza activity peaked during 2020 Weeks 6-7 and dropped rapidly beginning in Week 12, matching trends reported by CDC for influenza activity (Figure 1). Testing revealed 23,357 influenza positives out of 162,102 tests performed (14.4%). 17% of laboratory-confirmed influenza cases were hospitalized (compared to 23% during the prior season) with a median length of 3 days. Total influenza positives, telephone triage encounters, outpatient visits and antiviral use were higher than the prior season, whereas coded hospitalizations and deaths were fewer (Table, Figure 2). Conclusion: The 2019-20 influenza season was of moderate severity when compared to prior seasons and continues to track well with national CDC data. Overall, vaccination levels have increased modestly and high-dose/adjuvanted vaccine administration increased from 6 to 26% of total vaccine given over the seasons evaluated. Influenza activity dropped precipitously after Week 12 even though testing for influenza remained high in the setting of COVID-19. This may have been influenced by widespread social distancing and masking measures adopted in response to COVID-19. (Table Presented).